From the prior art, DE 102 20 557 A1 is known, which shows a manually operable medium dispenser having an actuating device. The actuating device is equipped with a slide valve, which is operated on a path-dependent basis and is activated by a relative movement between a piston rod and a control spike fitted in a pump cylinder. Since a pump chamber essentially limited by the pump cylinder and a piston packing is closed in a starting state via the path-dependent-operating slide valve, the medium enclosed in the pump chamber is pressurized upon actuation of the piston rod. Consequently, a relative movement of the piston packing relative to the piston rod takes place. As a result of the relative movement, a spring which serves as a loading means and is in operative connection with the piston packing is pretensioned, a force equilibrium existing between a tension of the spring and a pressure in the medium. As soon as the piston rod has covered a predetermined path, the slide valve opens due to the relative movement between piston rod and control spike, so that the medium pressurized by the spring can be discharged. The aim of this is to obtain a discharge of the medium which is independent of an actuating method.